1. Field of the Invention
The present invention relates to ultrasonic surgical probes or scalpels for use in the removal of inorganic or organic tissue from a living body, and, more particularly, to an ultrasonic surgical tool or needle capable of imparting ultrasonic vibrations to tissue and calculi in a living body, such as a tumor, cataract or stone, to fragment the tissue or calculi, and of removing fragmented tissue, calculi and fluids from the surgical site.
2. Description of Related Art
Ultrasonic probes or scalpels for the fragmentation and removal of inorganic materials and fluids from living beings are known to the art. For example, U.S. Pat. No. 2,227,727, issued Jan. 7, 1941 to Vincent Leggiardro, discloses an apparatus for fragmenting naturally formed stones, such as bladder stones, kidney stones, and the like, utilizing a high speed reciprocating rod which may have a blunt end, a sharp or chisel point end, a cutting blade, or combinations thereof, such as a cutting blade having a blunt end.
While the apparatus disclosed in U.S. Pat. No. 2,227,727 involved a two part housing, with the sonic transducer in one part and the reciprocating rod in another part, in later apparatus the transducer and probe were connected together to form a unitary instrument. In U.S. Pat. No. 3,896,811, issued Jul. 29, 1975 to Karl Storz, the transducer and rod-like probe are coupled and both are enveloped by a jacket providing an air gap and preventing the sides of the probe from contacting the body except at its end. Furthermore, the probe may have a scalloped end to effect the dissolution or break-up of stones.
An improvement in such instruments is disclosed in U.S. Pat. No. 3,990,452, issued Nov. 9, 1976 to Edward J. Murry and Joseph F. Brumbach, which also reviews a number of articles relating to the development of ultrasonics in medicine and, particularly for use in cataract surgery, and notes the incorporation of irrigation and aspiration with ultrasonics.
A particular arrangement in an ultrasonically vibrated surgical tool using an irrigation fluid and an anti-coagulant, is disclosed in U.S. Pat. No. 4,493,694, issued Jan. 15, 1985 to David G. Wuchinich, utilizes a hollow tool having a suction passage and at least one pre-aspirating orifice in the wall of the tool, and a sleeve concentrically spaced about the tool for admitting fluid from a supply into the space between the sleeve and the tool and passing substantially all of the fluid through the pre-aspirating orifice.
Although the arrangement of having substantially all of the fluid pass through the pre-aspirating orifice, as in U.S. Pat. No. 4,493,694, may be useful in some operations, it is often preferable to have a substantial portion of the irrigating fluid flow to or spray the surgical site to assist in washing the fragmented material or tissue and any excess blood from the site into the end of the tool assisted by suction. In the arrangement where a substantial portion of the irrigating fluid desirably flows to or is sprayed on the surgical site, an anticoagulant is not employed as such an additive may cause excessive bleeding at the site. In one commercial ultrasonic probe, a shorter sleeve is employed, such that the open end of the sleeve does not cover the pre-aspiration orifice, and no anticoagulant is used, and thereby the surgical site is irrigated to assist the removal of material from the site without causing excessive bleeding due to an anticoagulant.
However, none of these arrangements are completely satisfactory, particularly where the volume of irrigation and other conditions of operation of the tool varies as selected by the surgeon and with the surgical procedure. Therefore, there is a need for an improved ultrasonic surgical tool construction which provides for improved fragmentation of tissue and calculi, and which can provide for a consistent, substantial flow of irrigation fluid at the operating end of the tool under various operating parameters, while providing improved operation of the tool.